Description from Flora of China
Amethystanthus macrophyllus Migo, J. Shanghai Sci. Inst. 3: 230. 1937.
Herbs or subshrubs, perennial. Stems numerous, 1-1.5 m tall, woody at base, densely floccose-puberulent. Petiole (1-)3-5 cm, densely puberulent; blade of stem leaves subcircular to orbicular-ovate, occasionally broadly lanceolate, (5.5-)10-15 × (4.7-)5-10 cm, papery, adaxially puberulent, glabrescent, densely puberulent along veins, abaxially densely tomentulose, base cuneate to rounded, abruptly attenuate, margin coarsely crenate-serrate, apex excised, apical tooth narrowly lanceolate 2-2.5 cm; lateral veins ca. 4-paired, elevated abaxially. Panicles terminal or axillary, to 15 cm; cymes 10-15-flowered, pedunculate, densely pubescent; floral leaves bractlike, spatulate; bracteoles minute, linear, ca. 1 mm, densely pubescent. Calyx campanulate, 2.2-2.4 mm, densely pubescent outside, slightly 2-lipped; lower 2 teeth ovate-triangular, 1-1.5 mm, apiculate; upper 3 teeth smaller; fruiting calyx dilated, obviously veined, 2-lipped to 1/3 its length. Corolla bluish or purplish, 5-6 mm, tube ca. 2.5 mm. Stamens exserted. Style exserted. Nutlets obovoid, ca. 2.5 mm, hairy, glandular. Fl. and fr. Sep-Oct.
* Anhui, Jiangsu.